Message-id: <1365034495.4353.14.camel@kjgkr>
Subject: Re: [PATCH] To add NULL pointer check
From: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Reply-to: jaegeuk.kim@samsung.com
To: P J P <ppandit@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Petr Matousek <pmatouse@redhat.com>
Date: Thu, 04 Apr 2013 09:14:55 +0900
In-reply-to: <alpine.LFD.2.03.1304031342550.23577@erqung.pbz>
References: <alpine.LFD.2.03.1304021808410.12716@erqung.pbz>
 <1364958193.4353.4.camel@kjgkr>
 <alpine.LFD.2.03.1304031224180.21402@erqung.pbz>
 <1364975688.4353.7.camel@kjgkr>
 <alpine.LFD.2.03.1304031342550.23577@erqung.pbz>
Organization: samsung
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Hi,

2013-04-03 (=EC=88=98), 14:43 +0530, P J P:
> +-- On Wed, 3 Apr 2013, Jaegeuk Kim wrote --+
> | I'm confusing the question because f2fs doesn't use generic_writepages(=
),=20
> | since f2fs_write_data_pages() is linked to a_ops->writepages. In=20
> | do_writepages(), always f2fs_write_data_pages() is triggered instead of=
=20
> | generic_writepages(). Isn't it?
>=20
> Before commit fa9150a84c, when `generic_writepages' returned 0, it did no=
t=20
> abort `f2fs_write_data_pages', as the proposed patch does. I was wonderin=
g if=20
> that's intentional OR if the patch below does it right?
>=20
> =3D=3D=3D
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 7bd22a2..7be750e 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -561,7 +561,7 @@ static int f2fs_write_data_pages(struct address_space=
=20
> *mapping,
>  {
>         struct inode *inode =3D mapping->host;
>         struct f2fs_sb_info *sbi =3D F2FS_SB(inode->i_sb);
> -       int ret;
> +       int ret =3D 0;
>         long excess_nrtw =3D 0, desired_nrtw;
> =20
>         if (wbc->nr_to_write < MAX_DESIRED_PAGES_WP) {
> @@ -572,7 +572,9 @@ static int f2fs_write_data_pages(struct address_space=
 *mapping,
> =20
>         if (!S_ISDIR(inode->i_mode))
>                 mutex_lock(&sbi->writepages);
> -       ret =3D write_cache_pages(mapping, wbc, __f2fs_writepage, mapping=
);
> +       /* deal with chardevs and other special file */
> +       if (mapping->a_ops->writepage)
> +               ret =3D write_cache_pages(mapping, wbc, __f2fs_writepage,=
 mapping);

Why should we take unnecessary locks and an f2fs_submit_bio call?
Thanks,

>         if (!S_ISDIR(inode->i_mode))
>                 mutex_unlock(&sbi->writepages);
>         f2fs_submit_bio(sbi, DATA, (wbc->sync_mode =3D=3D WB_SYNC_ALL));
> =3D=3D=3D
>=20
> Thank you.
> --
> Prasad J Pandit / Red Hat Security Response Team
> DB7A 84C5 D3F9 7CD1 B5EB  C939 D048 7860 3655 602B
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" i=
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> the body of a message to majordomo@vger.kernel.org
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--=20
Jaegeuk Kim
Samsung

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